Enclosed proximity switch assembly

ABSTRACT

An enclosed proximity switch assembly includes a top enclosure and a bottom enclosure that are coupled to form an interior volume. A shaft protrusion upwardly extends from a top surface of the top enclosure, and an interior bore portion having an enclosed volume is defined within the shaft protrusion to form a portion of the interior volume. A first end of a vertical shaft is rotatably disposed within the interior bore portion such that the shaft rotates relative to the top and bottom enclosures. A samarium cobalt target magnet is coupled to the shaft, and the target magnet interacts with a samarium cobalt driver magnet within a proximity switch when the target magnet is rotated within a predetermined distance of a top portion of the proximity switch. The interaction causes a switch to move from a first state to a second state, or vice versa.

FIELD OF THE DISCLOSURE

This disclosure relates generally to an enclosure, and, moreparticularly, to a sealed enclosure containing at least one magnetictarget that is detected by at least one magnetic proximity switch.

BACKGROUND

Magnetic proximity switches, also known as limit switches, are commonlyused for position sensing. Typically, a magnetic proximity switchassembly includes a target and a proximity switch, with the proximityswitch including a switching circuit. The switching circuit may includean element, such as a lever, that is biased in a first position by apermanent magnet contained in the housing of the proximity switch. Withthe lever in this first position, the proximity switch is maintained ina first state, in which, for example, a normally closed contact makescontact with a common contact. When the target, which generally includesa permanent magnet, passes within a predetermined range of the proximityswitch, the magnetic flux generated by the target magnet causes thelever of the switching circuit to change bias from the first state to asecond state, in which, for example, a normally open contact makescontact with the common contact.

In some applications, one or more target magnets and one or moreproximity switches may be disposed within a sealed enclosure to protectthe proximity switches from damage. This configuration is common whenthe magnetic proximity switch assembly is used in hazardousenvironments, such as nuclear applications. In such applications, theenclosure is intended to withstand the high temperatures and pressuresthat occur during a containment accident or a LOCA (loss of coolantaccident) at a nuclear facility. Typically, a shaft vertically disposedwithin the enclosure supports the target magnet as the target magnetrotates with the shaft relative to a stationary proximity switch.Typically, a top portion of the shaft is coupled to a sealed top bearingassembly disposed within a top aperture that extends through a topportion of the enclosure, and a bottom portion of the shaft is receivedin a bottom aperture that extends through a bottom portion of theenclosure. The bottom portion of the shaft that extends through thebottom aperture is typically coupled to a valve element, such as therotating stem of a control valve used for a nuclear application, and therotation of the stem can be detected with the valve rotates the targetmagnet within a predetermined range of the proximity switch disposedwithin the enclosure, thereby indicating the control valve is in aparticular position. Alternatively, the rotating stem of the controlvalve may move the target magnet out of a predetermined range of theproximity switch, thereby indicating the control valve has moved from aparticular position.

Due to the hazardous environments in which the magnetic proximity switchassembly is used, the enclosure must be sealed to avoid allowing hightemperature gas under high pressure, or other contaminants, into theenclosure. Moreover, due to loads that may occur during a seismic event,components such as the proximity switch and/or an assembly that securesthe target magnet to the shaft must be adequately secured within theenclosure to prevent unintended displacement that may occur as a resultof the seismic loads.

BRIEF SUMMARY OF THE DISCLOSURE

In accordance with one exemplary aspect of the present invention, atarget support for supporting a target magnet within an enclosedproximity switch assembly includes a hub having a body portion thatextends along a longitudinal axis, the body portion including an outersurface and a shaft aperture that extends along the longitudinal axis.The shaft aperture is adapted to receive a portion of a shaft thatextends along the longitudinal axis, and the body portion furtherincludes one or more threaded body apertures that extend from the outersurface to the shaft aperture. The target support further includes amagnet support non-rotatably secured to the hub, the magnet supporthaving a base portion that extends in a direction normal to thelongitudinal axis, and the base portion includes a planar top surface. Aside wall upwardly extends from the top surface of the base portion, andthe side wall is partially defined by an inner surface. The targetsupport also includes one or more target magnets disposed on the topsurface of the base portion of the magnet support between a portion ofthe hub and the inner surface of the side wall of the magnet support. Inaddition, the target support includes a clamp plate, and the clamp platehas a planar bottom surface and a shaft aperture adapted to receive aportion of the shaft, and the clamp plate is secured to the hub suchthat the bottom surface of the clamp plate is immediately adjacent to orin contact with a top surface of the hub and such that the bottomsurface of the clamp plate is also immediately adjacent to or in contactwith a top surface of the one or more target magnets. The target supportalso includes a set screw adapted to threadably engage one of the one ormore body apertures such that a distal end of the set screw contacts anouter surface of the shaft to non-rotatably secure the target support tothe shaft. A minimum torque of 150 inch-ounces is applied to the setscrew, and the set screw is sealed within the one of the one or morebody apertures with a high-temperature potting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the exterior of an embodiment of anenclosed proximity switch assembly;

FIG. 2 is a top view of the embodiment of the enclosed proximity switchassembly of FIG. 1;

FIG. 3 is a sectional side view of the enclosed proximity switchassembly taken along section line 3-3 of FIG. 2;

FIG. 4 is a side view of the shaft protrusion of FIG. 3 with the shaftomitted for clarity;

FIG. 5 is a side view of a shaft of the embodiment of the enclosedproximity switch assembly of FIG. 1;

FIG. 6 is a sectional side view of the enclosed proximity switchassembly taken along section line 6-6 of FIG. 2;

FIG. 7A is a perspective view of the embodiment of the enclosedproximity switch assembly of FIG. 1 with the top enclosure removed forclarity;

FIG. 7B is a side view of the target support of the embodiment of theenclosed proximity switch assembly of FIG. 1;

FIG. 8 is an exploded perspective view of a proximity switch of theembodiment of the enclosed proximity switch assembly illustrated in FIG.1;

FIG. 9 is an side view of a switch assembly of the proximity switch ofFIG. 8;

FIG. 10A is a schematic view of the proximity switch of FIG. 8 in afirst state;

FIG. 10B is a schematic view of the proximity switch of FIG. 8 in asecond state;

FIG. 11A is a top view of the target magnet and the proximity switch ina first shaft position;

FIG. 11B is a top view of the target magnet and the proximity switch ina second shaft position;

FIG. 12A is an exploded perspective view of an embodiment of a targetsupport;

FIG. 12B is a perspective view of the embodiment of the target supportof FIG. 12A;

FIG. 13A is front view of a hub of the target support of FIG. 12A;

FIG. 13B is partial sectional front view of a set screw in a bodyaperture of the hub of FIG. 13A; and

FIG. 14 is a perspective view of an embodiment of a housing of aproximity switch.

DETAILED DESCRIPTION

As illustrated in FIG. 3, an enclosed proximity switch assembly 10includes a top enclosure 12 having a base wall 14 and a plurality ofside walls 16 that extend downwardly from the base wall 14, and the basewall 14 and the plurality of side walls 16 may at least partially definea first volume 18. A shaft protrusion 20 may upwardly extend from a topsurface 22 of the base wall 14, and an interior bore portion 24 may bedefined within the shaft protrusion 20 such that the interior boreportion 24 forms a portion of the first volume 18. The interior boreportion 24 may define an enclosed volume. The proximity switch assembly10 also includes a bottom enclosure 28 having a base wall 30 and aplurality of side walls 32 that extend upwardly from the base wall 30,and the base wall 30 and the plurality of side walls 32 at leastpartially define a second volume 34. A shaft aperture 36 may be definedin the base wall 30, the shaft aperture 36 may extend through the basewall 30. The top enclosure 12 may be coupled to the bottom enclosure 28such that the first volume 18 and the second volume 34 cooperate todefine an interior volume 38. So configured, a longitudinal axis 40 ofthe shaft aperture 36 may be aligned with a longitudinal axis 42 of theinterior bore portion 24. The proximity switch assembly 10 also includesa shaft 44 having a first end 46, a second end 48 opposite the first end46, and a first intermediate portion 50 between the first end 46 and thesecond end 48, wherein the first end 46 of the shaft is disposed withinthe interior bore portion 24 formed in the shaft protrusion 20 of thetop enclosure 12. The first intermediate portion 50 of the shaft 44 mayextend through the shaft aperture 36 formed in the bottom enclosure, andthe second end of the shaft may be disposed exterior to the interiorvolume 38. The shaft 44 is rotatable relative to the top enclosure 12and the bottom enclosure 28. In addition, the proximity switch assembly10 includes a target support 52 non-rotatably coupled to a secondintermediate portion 54 of the shaft 44, the second intermediate portion54 being disposed between the first intermediate portion 50 and thefirst end 46 of the shaft 44. The target support 52 including a radialportion 56 that extends away from the shaft, and a target magnet 58 maybe coupled to the radial portion 56 of the target support 52. Asillustrated in FIGS. 3 and 8 to 11B, the proximity switch assembly 10includes at least one proximity switch 60 disposed within the interiorvolume 38 and coupled to the bottom enclosure 28 such that when theshaft 44 is in a first shaft position 61, the target magnet 58 isdisposed a distance away from a top portion 64 of the at least oneproximity switch 60, thereby causing the proximity switch 60 to be in afirst state 66. When the shaft 44 is rotated into a second shaftposition 63, the target magnet 58 is disposed adjacent to the topportion 64 of the at least one proximity switch 60, thereby causing theproximity switch to be in a second state 70. Each of the first andsecond states 66, 70 may correspond to a position of a valve elementthat is coupled to the second end 48 of the shaft 44.

As illustrated in FIGS. 1, 2, 3, and 6, the enclosed proximity switchassembly 10 may include a top enclosure 12 that may include a base wall14. The base wall 14 of the top enclosure 12 may be rectangular in shapeand may be substantially planar, and the plane formed by the base wall14 may be substantially horizontal. As used herein, the term“horizontal” indicates a direction that is substantially coplanar withor substantially parallel to the X-Y plane of the reference coordinatesystem illustrated in FIG. 1. The term “vertical” indicates a directionthat is substantially normal to the X-Y plane (i.e., the direction ofthe Z axis) of the reference coordinate system illustrated in FIG. 1.Instead of a horizontally disposed base wall 14, the planar base wall 14may be obliquely disposed relative to the X-Y plane. In addition, ratherthan the planar configuration illustrated in FIG. 1, the base wall 14may have any shape suitable for a particular application. For example,the base wall 14 may have a curved cross-sectional shape or may beotherwise contoured, or the base wall 14 may be partiallycurved/contoured and partially planar. In addition, the base wall 14 mayinclude two or more planar portions that are vertically offset (notshown) to form a stepped surface.

Referring again to FIGS. 1, 2, 3, and 6, the top enclosure 12 mayinclude a plurality of side walls 16 that extend downwardly from thebase wall 14. More specifically, the plurality of downwardly extendingside walls 16 may include a first wall 72 that extends from a firstperimeter edge 74 of the base wall 14. A second wall 76 may extend froma second perimeter edge 78 of the base wall 14, and the second perimeteredge 78 may be disposed opposite from the first perimeter edge 74. Athird wall 80 may extend from a third perimeter edge 82 of the base wall14, and the third perimeter edge 82 may extend between the first andsecond perimeter edges 74, 78. A fourth wall 84 may extend from a fourthperimeter edge 86 of the base wall 14 that is opposite to the thirdperimeter edge 82, and the fourth perimeter edge 86 may extend betweenthe first and second perimeter edges 74, 78. Each of the plurality ofside walls 16 may extend obliquely away from the base wall 14, asillustrated in FIGS. 1, 2, 3, and 6. However, any or all of theplurality of side walls 16 may extend away from the base wall 14 in anysuitable manner or direction, such as perpendicularly, for example.While each of the plurality of side walls 16 is illustrated as planar inFIGS. 1-3, any or all of the plurality of side walls 16 may have anysuitable shape, such as contoured, or partially planar or partiallycontoured. Moreover, the plurality of side walls 16 may include more (orfewer) walls than illustrated in FIGS. 1, 2, 3, and 6. An upper flange88 may horizontally extend from a bottom portion of each of theplurality of side walls 16, and the upper flange 88 may have a pluralityof mating apertures 90 a disposed therein, the mating apertures 90 aadapted to receive bolts that couple the top enclosure 12 to the bottomenclosure 28. As configured, the base wall 14 and the plurality ofdownwardly extending side walls 16 may at least partially define a firstvolume 18.

As illustrated in FIGS. 1, 3, 4, and 6, the top enclosure 12 may includea shaft protrusion 20 that upwardly extends from a top surface 22 of thebase wall 14. The shaft protrusion 20 may include an outer surface 90and the outer surface 90 may have any suitable shape or combination ofshapes. For example, the outer surface 90 may have a circularcross-sectional shape such that the outer surface 90 is cylindrical.Alternatively, the outer surface 90 may have the cross-sectional shapeof an oval or a polygon, for example. The shaft protrusion 20 may alsohave a top surface 92, and the top surface 92 may be planar. However,the top surface 92 may have any suitable shape or combination of shapes,such as the shape of a cone or the shape of a hemisphere, for example.An inner side surface 94 may partially define an interior bore portion24 of the of the shaft protrusion 20, and the interior bore portion 24may be adapted to receive the first end 46 of the shaft 44 in a mannerthat allows the shaft 44 to rotate relative to the top enclosure 12. Theinner side surface 94 may have any suitable shape or combination ofshapes. For example, the inner side surface 94 may have a circularcross-sectional shape such that the inner side surface 94 iscylindrical. The cylindrical inner side surface 94 may have alongitudinal axis 42, and the cylindrical inner side surface 94 may besized to receive the first end 46 of the shaft 44. The interior boreportion 24 of the shaft protrusion 20 may be further defined by an innertop surface 96, and the inner top surface 96 may have any suitable shapeor combination of shapes. For example, the inner top surface 96 may beconical, planar, or hemispherical. As configured, the inner side surface94 and the inner top surface 96 cooperate to at least partially definean enclosed volume (i.e., the interior bore portion 24) within the shaftprotrusion 20 that forms a portion of the first volume 18. Because theinterior bore portion 24 is an enclosed volume that is not in fluidcommunication with the exterior of the top enclosure 12, the interiorbore portion 24 forms a blind bore that is adapted to receive the firstend 46 of the shaft 44 without providing a potential leakpath betweenthe interior bore portion 24 and the exterior of the top enclosure 12.

As illustrated in FIGS. 1, 3, and 6, the enclosed proximity switchassembly 10 may also include a bottom enclosure 28 that may include abase wall 30. The base wall 30 of the bottom enclosure 28 may berectangular in shape and may be substantially planar, and the planeformed by the base wall 30 may be substantially horizontal and parallelto the base wall of the 14 of the top enclosure 12. Instead of ahorizontally disposed base wall 30, the planar base wall 30 may beobliquely disposed relative to the X-Y reference plane illustrated inFIG. 1. In addition, rather than the planar configuration illustrated inFIG. 1, the base wall 30 may have any shape suitable for a particularapplication. For example, the base wall 30 may have a curvedcross-sectional shape or may be otherwise contoured, or the base wall 30may be partially curved/contoured and partially planar. In addition, thebase wall 30 may include two or more planar portions that are verticallyoffset (not shown) to form a stepped surface.

Referring again to FIGS. 1, 3, and 6, the bottom enclosure 28 mayinclude a plurality of side walls 32 that extend upwardly from the basewall 30. More specifically, the plurality of upwardly extending sidewalls 32 may include a first wall 94 that extends from a first perimeteredge 96 of the base wall 30. A second wall 98 may extend from a secondperimeter edge 100 of the base wall 30, and the second perimeter edge100 may be disposed opposite from the first perimeter edge 96. A thirdwall 102 may extend from a third perimeter edge 104 of the base wall 30,and the third perimeter edge 104 may extend between the first and secondperimeter edges 96, 100. A fourth wall 106 may extend from a fourthperimeter edge 108 of the base wall 30 that is opposite to the thirdperimeter edge 104, and the fourth perimeter edge 108 may extend betweenthe first and second perimeter edges 96, 100. Each of the plurality ofside walls 32 may extend obliquely away from the base wall 30, asillustrated in FIGS. 1, 3, and 6. However, any or all of the pluralityof side walls 32 may extend away from the base wall 30 in any suitablemanner or direction, such as perpendicularly, for example. While each ofthe plurality of side walls 32 is illustrated as planar in FIGS. 1, 3,and 6, any or all of the plurality of side walls 32 may have anysuitable shape, such as contoured, or partially planar or partiallycontoured. Moreover, the plurality of side walls 32 may include more (orfewer) walls than illustrated in FIGS. 1, 3, and 6. As configured, thebase wall 30 and the plurality of downwardly extending side walls 32 mayat least partially define a second volume 34.

Referring again to FIGS. 1, 3, and 6, the bottom enclosure 28 mayinclude one or more side apertures 128, and each side aperture 128 maybe formed at any appropriate location. For example, a side aperture 128may extend through one of the plurality of side walls 32, such asthrough the fourth wall 106. The side aperture 128 may be defined by aninterior surface that may be at least partially threaded such that afitting having a threaded exterior surface can engage the side aperture128. The side aperture 128 may have any suitable shape. For example, theside aperture 128 may have a circular cross-sectional shape. The sideaperture 128 may be sized to receive the fitting of a length of conduitthat is adapted to contain a plurality of wires that connects the one ormore proximity switches 60 to externally located hardware.

Referring again to FIGS. 1, 3, and 6, the bottom enclosure 28 mayinclude a shaft aperture 36 disposed through the base wall 30. The shaftaperture 38 may be sized to receive a first intermediate portion 50 ofthe shaft 44. Because the shaft aperture 36 extends through the basewall 30, the second volume 34 is in fluid communication with theexterior of the bottom enclosure 28 when the shaft 44 is not disposedthrough the shaft aperture 36. The shaft aperture 36 may be partiallydefined by an inner surface 120 of an upper boss portion 122 thatextends upwardly from the base wall 30. In addition, the shaft aperture36 may be further partially defined by an inner surface 124 of a lowerboss portion 122 that extends downwardly from the base wall 30. Theinner surface 120 of an upper boss portion 122 and the inner surface 124of a lower boss portion 122 may each be cylindrical such that the shaftaperture 28 has the overall shape of a cylinder having a longitudinalaxis 40. When the top enclosure 12 is coupled to the bottom enclosure asdescribed below, the longitudinal axis 42 of the interior bore portion24 is axially aligned with the longitudinal axis 40 of the shaftaperture 28.

Referring again to FIGS. 1, 3, and 6, a lower flange 110 mayhorizontally extend from a top portion of each of the plurality of sidewalls 32, and the lower flange 110 may have an engagement surface 112that engages a corresponding engagement surface 114 of the upper flange88. A seal 116 may be disposed in a recess that extends along the topportion of each of the plurality of side walls 32, and the seal 116 isadapted to prevent a leakpath between the engagement surface 112 oflower flange 110 and the engagement surface 114 of upper flange 88 whenthe top enclosure 12 is coupled to the bottom enclosure 28. The seal 116may be made from a radiation tolerant, high temperature siliconematerial. Instead of the seal 116 in a recess, any sealing arrangementmay be used. For example, a gasket may be disposed between theengagement surface 112 of lower flange 110 and the engagement surface114 of upper flange 88.

The top enclosure 12 may be coupled to the bottom enclosure 28 by anymeans known in the art. For example, the lower flange 110 may have aplurality of mating apertures 90 b disposed therein, the matingapertures 90 b being coaxially aligned with the mating apertures 90 a ofthe upper flange 88 such that each pair of mating apertures 90 a, 90 bmay receive a bolt 118 adapted to couple the top enclosure 12 to thebottom enclosure 28. The bolt 118 may have a threaded bottom portion,and the threaded bottom portion of the bolt may engage a threadedinterior portion of one or both of the mating apertures 90 a, 90 b.Assembled as described, the base wall 30 and the plurality of downwardlyextending side walls 32 may at least partially define a second volume34, and when the top enclosure 12 is secured to the bottom enclosure 28,the first volume 18 and the second volume 34 form an interior volume 38.

The top enclosure 12 and the bottom enclosure 28 may be manufacturedfrom any suitable materials. For example, the top enclosure 12 and thebottom enclosure 28 may be formed from a metal or a metal alloy, such asaluminum or 316 stainless steel. The metal or metal alloy enclosures 12,28 may be formed by any process or combination of processes, such as bycasting or machining. Alternatively, the top enclosure 12 and the bottomenclosure 28 may be made of plastic, and the enclosures 12, 28 may beformed from an injection molding process.

As illustrated in FIGS. 3, 5, and 6, the enclosed proximity switchassembly 10 may also include a shaft 44 that is rotatable relative tothe top enclosure 12 and bottom enclosure 28. The shaft may have anelongate shape having a first end 46 and a second end 48 opposite thefirst end 46. The first end 46 may have a circular cross-section shape,and the diameter of the circular cross-sectional shape of the first end46 may be slightly less than the diameter of the circularcross-sectional shape of the inner side surface 94 defining the interiorbore portion 24 of the shaft protrusion 20 of the top enclosure 12. Soconfigured, the first end 46 of the shaft is rotatably disposed withinthe enclosed interior bore portion 24. The shaft 44 may have a firstintermediate portion 50 disposed between the first end 46 and the secondend 48 of the shaft 44. The first intermediate portion 50 may have acircular cross-section shape, and the diameter of the circularcross-sectional shape of the first intermediate portion 50 is slightlyless than the diameter of the circular cross-sectional shape of theshaft aperture 28 such that the first intermediate portion 50 extendsthrough, and is rotatably disposed within, the shaft aperture 28. Soconfigured, the second end 48 of the shaft is disposed exterior to theinterior volume 38 formed by the top enclosure 12 and the bottomenclosure 28. For example, the second end 48 of the shaft 44 may extendbeyond the lower boss portion 126 that projects downwardly from the basewall 30 of the bottom enclosure 28. The shaft 44 may have any suitableshape or combination of shapes. For example, the shaft 44 may have asubstantially cylindrical shape having a substantially uniformcross-section shape.

As illustrated in FIGS. 3 and 6, the shaft 44 may be maintained in adesired position by a pair of snap rings 130 disposed in grooves formedin the first intermediate portion 50 of the shaft 44. One of the pair ofsnap rings 130 may be disposed adjacent to or contacting a distal end ofthe upper boss portion 122 and a second of the pair of snap rings 130may be disposed adjacent to or contacting a distal end of the lower bossportion 126, thereby preventing upward and/or downward displacement ofthe shaft 44 relative to the bottom enclosure 28. A seal 132, such as anO-ring, may be disposed in a recess that extends around thecircumference of the first intermediate portion 50 of the shaft 44. Theseal 132 is adapted to sealingly engage the inner surfaces 120, 124 thatdefine the shaft aperture 28 to prevent a leakpath between the firstintermediate portion 50 of the shaft 44 and the inner surfaces 120, 124.The seal 132 may be made from a radiation tolerant, high temperaturesilicone material.

As illustrated in FIGS. 3, 7A and 7B, the enclosed proximity switchassembly 10 may also include a target support 52. The target support 52may include a base portion 134 that is coupled to a second intermediateportion 54 of the shaft 44, with the second intermediate portion 54being disposed between the first end 46 and the first intermediateportion 50 of the shaft 44. More specifically, the base portion 134 mayhave an aperture 136 extending from a top portion to a bottom portion ofthe base portion 134, and the aperture 136 receives the secondintermediate portion 54 of the shaft 44. The base portion 134 may befixed to the shaft 44 such that the target support 52 rotates along withthe shaft 44, and the base portion 134 may be prevented from rotatingrelative to the shaft 44 by any means known in the art, such as, forexample, a set screw, a key and slot, or an interference fit. Inaddition, one or more snap rings (not shown) may be coupled to the shaft44 adjacent to the bottom portion of the base portion 134 to preventdownward displacement of the target support 52. The base portion 134 maybe permanently fixed to the shaft, of the base portion 134 may bereleasably secured to the such that the base portion 134 can bevertically repositioned relative to the shaft 44. The base portion 134have any suitable shape or combination of shapes. For example, the baseportion 134 may have a circular or ovular cross-sectional shape, or thebase portion 134 may have a polygonal cross-sectional shape, such asthat of a square or rectangle. The base portion 134 may be dimensionedsuch that when the target support 52 rotates with the shaft 44, the baseportion 134 does not contact any of the elements contained within theinterior volume, such as the one or more proximity switches 60.

Referring again to FIGS. 3, 7A and 7B, the target support 52 may alsoinclude a radial portion 56 coupled to the base portion 134 such thatthe radial portion 56 extends away from the shaft 44. The radial portion56 may have any shape or combination of shapes suitable for a givenapplication. For example, the radial portion 56 may be a cantileveredprojection extending from the base portion 134, and the radial portion56 may have a rectangular cross-sectional shape. If the target support52 includes more than one radial portions 56 are used, each radialportion may be a cantilevered projection extending from the base portion134. Each radial portion 56 may include a target aperture 138 extendingtherethrough, and a longitudinal axis of the target aperture 138 may besubstantially vertical. The target aperture 138 may be sized to receivea target magnet 58. The target magnet 58 may have any shape or sizesuitable for a particular application. For example, the target magnet 58may have a cylindrical shape, and the depth of the cylinder may be lessthan the vertical height of the radial portion 56 such that the targetmagnet 58 may be vertically adjusted within the target aperture 138. Thetarget magnet 58 may be secured within the target aperture 138 by anymeans known in the art, such as by an adhesive, or by a magnetic force.In addition, the target aperture 138 may be a blind bore having a bottomportion of a reduced thickness to support the target magnet 58. Thetarget aperture 138, and the target magnet 58 disposed therein, may bepositioned at any suitable location on the radial portion 56. Forexample, the target aperture 138 may be disposed on the radial portion56 such that when the radial portion 56 is rotated to a position above aproximity switch 60, at least a portion of the target magnet 58 isdisposed above or adjacent to a top portion 64 of a proximity switch 60.However, the target aperture 138 may be disposed at any location on theradial portion 56 that allows the target magnet 58 to be detected by theproximity switch 60 in a manner that will be described in more detailbelow. The target magnet 58 may be any type of magnet suitable for aparticular application, such as a samarium cobalt magnet.

An alternative embodiment of the target support 52 is illustrated inFIGS. 12A and 12B. In this embodiment, the target support 52 includes amagnet support 200, a hub 202, and a clamp plate 204. The hub 202,illustrated in FIG. 13A, may include a body portion 206 that extendsalong a longitudinal axis 207 from a first end 208 to a second end 210.The body portion 206 may also have a shaft aperture 209 that extendsalong the longitudinal axis 207 from the first end 208 of the bodyportion 206 to the second end 210 body portion 206, and the shaftaperture 210 may sized to receive the second intermediate portion 54 ofthe shaft 44. The body portion 206 may be elongated and may have acylindrical outer surface 212 that is coaxially aligned with thelongitudinal axis 207 of the body portion 206. However, the outersurface 212 of the body portion 206 may have any suitable shape, such asthe shape of a polygon or an oval when viewed in cross-section along thelongitudinal axis 207 of the body portion 206. One or more bodyapertures 213 may extend in a radial direction (i.e., normal to andintersecting the longitudinal axis 207) from the outer surface 212 ofthe body portion 206 to the shaft aperture 210. For example, asillustrated in FIG. 13A, the body portion 206 may include four bodyapertures, with a first and second body aperture 213 a, 213 b beinglongitudinally aligned and offset by a suitable longitudinal distance. Athird body aperture 213 c may be radially aligned with the first bodyaperture 213 a such that a longitudinal axis of the third body aperture213 c is coaxially aligned with a longitudinal axis of the first bodyaperture 213 a, and the longitudinal axis of each of the first bodyaperture 213 a and the third body aperture 213 c intersects thelongitudinal axis 107. A fourth body aperture 213 d may be radiallyaligned with the second body aperture 213 b such that a longitudinalaxis of the fourth body aperture 213 d is coaxially aligned with alongitudinal axis of the second body aperture 213 b, and thelongitudinal axis of each of the fourth body aperture 213 d and thesecond body aperture 213 b intersects the longitudinal axis 107. Each ofthe body apertures 213 may be internally threaded and dimensioned toreceive and threadedly engage a corresponding set screw 220 that will bedescribed in more detail below.

As illustrated in FIG. 13A, the hub 202 of the target support 52 mayalso include a flange portion 214 that radially extends from the firstend 208 of the body portion 206. More specifically, the flange portion214 may include top surface 215 that may be planar and may be normal tothe longitudinal axis 207. The top surface 215 may have a circularperimeter edge 216, and the diameter of the perimeter edge 216 may begreater than the diameter of the outer surface 212 of the body portion206. A flange surface 218 may downwardly (i.e., towards the second end210 of the body portion 206) extend from the perimeter edge 216 or froma cylindrical side surface 222 that downwardly extends from theperimeter edge 216, and the flange surface 218 may gradually taper tointersect the outer surface 212 of the body portion 206 such that theflange surface 218 has a frustoconical shape. One or more flangeapertures 224 may inwardly extend from the top surface 215 of the flangeportion 214 in a direction parallel to the longitudinal axis 207. Forexample, three flange apertures 224 may be symmetrically disposed aboutthe longitudinal axis 207. Each flange aperture 224 may be internallythreaded and dimensioned to receive and threadedly engage acorresponding top screw 226 that will be described in more detail below.

Referring to FIGS. 12A and 12B, the target support 52 may also includethe magnet support 200 that is non-rotatably secured to (or integrallyformed with) the hub 202. The magnet support 200 may include a baseportion 228, and the base portion may extend in a direction normal tothe longitudinal axis 207. The base portion 228 may have a disc-likeshape such that base portion 228 has a planar top surface 230 and aplanar bottom surface 232. The base portion 228 may also have a centralaperture 234 that extends from the top surface 230 to the bottom surface232. The central aperture 234 may have a cylindrical inner surface 238,and the longitudinal axis of the cylindrical inner surface 238 may becoaxially aligned with the longitudinal axis 107. The central aperture234 may receive the body portion 206 of the hub 202, so the diameter ofthe inner surface 238 may be slightly greater than the diameter of theouter surface 212 of the body portion 206. The magnet support 200 mayalso include a side wall 236 that upwardly extends from the top surface230 of the base portion 228 adjacent to a circumferential edge of thebase portion 228, and the side wall 236 may be partially defined by aninner surface 238, and the inner surface 238 may have the shape of acylinder that is coaxially aligned with the longitudinal axis 107.

To secure the hub 202 to the magnet support 200 as illustrated in FIG.12A, the body portion 206 of the hub 202 may received into the centralaperture 234 of the magnet support 200 such that the tapered flangesurface 218 contacts a portion of the base portion 228 adjacent the topsurface 230. So positioned, the second end 210 of the hub 202 extendsbelow the bottom surface 232 of the base portion 228 of the magnetsupport 200 to form a shoulder. The hub 202 may then be secured to themagnet support 200 by any manner known in the art such that no relativerotation or relative longitudinal displacement occurs between the hub202 and the magnet support 200 during use of the assembly 10. Forexample, the base portion 228 may be welded to the body portion 206 ofthe hub 202, or a snap ring (not shown) may be disposed in acircumferential groove formed in the body portion 206 immediatelyadjacent to the bottom surface 230 of the base portion 228 of the magnetsupport 200. In addition, an interference fit between the centralaperture 234 of the base portion 228 and the outer surface 212 of thebody portion 206 of the hub 202 may non-rotatably couple the magnetsupport 200 and the hub 202. In alternative embodiments, the hub 202 andthe magnet support 200 may be integrally formed as a single, unitarypart such that the body portion 206 of the hub 202 extends from thebottom surface 232 of the base portion 228 of the magnet support 200.

As illustrated in FIG. 12A, one or more target magnets 58 may bedisposed on the top surface 230 of the base portion 228 of the magnetsupport 200. More specifically, the one or more target magnets 58 mayeach be disc-shaped, and the diameter of the disc may be slightly lessthan the radial distance between the perimeter edge 216 of the flangeportion 214 of the hub 202 and the inner surface 238 of the side wall236 of the magnet support 200. As such, each of the one or more targetmagnets 58 may be disposed at a desired location on the top surface 230of the base portion 228 between the perimeter edge 216 of the flangeportion 214 and the inner surface 238 of the side wall 236, and such adesired location may be any suitable location that allows the targetmagnet 58 to be detected by the proximity switch 60 in a manner thatwill be described in more detail below. An O-ring 250 may be disposedaround the circumference of the flange portion 214 such that the O-ring250 contacts at least a portion of the flange surface 218, a portion ofthe top surface 230 of the base portion 228, and a portion of the targetmagnet 58 to secure the target magnet 58 in a desired location when thetarget support 52 is assembled.

Referring to FIGS. 12A and 12B, the target support 52 may also includethe clamp plate 204, and the clamp plate 204 may have a planar topsurface 240, a planar bottom surface 242, and a shaft aperture 244adapted to receive a portion of the shaft 44. The clamp plate 204 mayhave a circular perimeter edge 246 such that the clamp plate 204 has adisc-like shape and a longitudinal axis of the shaft aperture 244 isaligned with the center of the circular perimeter edge 246. The diameterof the perimeter edge 246 may be slightly less than the diameter of theinner surface 238 of the side wall 236 of the magnet support 200. Theclamp plate 204 may include one or more clamp apertures 248 that mayextend from the top surface 240 to the bottom surface 242 in a directionparallel to the longitudinal axis 207. The clamp apertures 248 maycorrespond in number, diameter, and relative position to the flangeapertures 224 disposed in the flange portion 214 of the hub 202.

With the one or more target magnets 58 positioned as desired on the topsurface 230 of the base portion 228 of the magnet support 200, thebottom surface 242 of the clamp plate 204 may be moved into contact withor immediately adjacent to the top surface 215 of the flange portion 214of the hub 202 such that each of the clamp apertures 248 is aligned witha corresponding flange aperture 224 of the flange portion 214 of the hub202 and such that the shaft aperture 244 of the clamp plate 204 iscoaxially aligned with the shaft aperture 209 of the hub 202, asillustrated in FIG. 12A. A top screw 226 is inserted into each of theclamp apertures 248 and is rotated to threadedly engage thecorresponding flange aperture 224 to secure the magnet support 200 tothe clamp plate 204. Each of the top screws 226 may be torqued a minimumof 160 inch-ounces to ensure proper engagement. So configured, thebottom surface 242 of the clamp plate 204 may contact or may beimmediately adjacent to a top surface of each of the one or more targetmagnets 58 to secure or further secure the target magnets 58 in adesired position.

To secure the target support 52 to the shaft 44, the shaft 44 isinserted into the shaft aperture 244 of the clamp plate 204 and theshaft aperture 209 of the hub 202 such that the longitudinal axis of theshaft 44 (and the longitudinal axis 42 of the interior bore portion 24as illustrated in FIG. 3) is coaxially aligned with the longitudinalaxis 207. The target support 52 is subsequently longitudinallypositioned at a desired location that will be described in more detailbelow. A set screw 220 is inserted into each of the body apertures 213formed in the body portion 206 of the hub 202 (such as the first,second, third, and fourth body apertures 213 a, 213 b, 213 c, 213 d). Asillustrated in FIG. 13B, each set screw 220 is then rotated tothreadedly engage the corresponding body aperture 213 until a distal end251 of the set screw 220 contacts the outer surface 253 of the shaft 44.A minimum torque of 150 inch-ounces is applied to each set screw 220 tofully secure the hub 202 to the shaft 44. Each of the set screws 220 issealed with a high-temperature potting to further secure the set screws220 within the corresponding body aperture 213. The potting may beapplied to the set screw and/or the body aperture 213 prior to insertingthe set screw 220 within the body aperture 213. Alternatively, thepotting may be applied after the set screw 220 is fully received withinthe body aperture. The potting may be an epoxy, such as DURALCO® 4525,for example. The potting may air dry or may be heated to dry. Theminimum torque specification in conjunction with the potting assist inmaintaining the set screws 220 in engagement with the shaft 44 (andthereby preventing longitudinal displacement of the target support 52relative to the shaft 44) when the enclosed proximity switch assembly 10is subjected to seismic testing or any other seismic event. One havingordinary skill in the art would recognize that the minimum torquespecification in conjunction with the described potting can also beemployed with any embodiment of a target support. For example, referringto the target support 52 illustrated in FIGS. 7A and 7B, one or morebody apertures would each extend from an outer surface of the base (orbody) portion 134 to the aperture 136 to receive a set screw 220.

As illustrated in FIGS. 3, 7A, 8, and 9, the enclosed proximity switchassembly 10 may also include one or more proximity switches 60 coupledto the bottom enclosure 28. The proximity switch 60 may include ahousing 140 having any suitable shape for a given application. Forexample, the housing 140 may include a planar first side wall 142 and aplanar second side wall 144 parallel to and offset from the first sidewall 142. A planar third side wall 146 may extend perpendicularlybetween the first side wall 142 and the second side wall 144 along afirst lateral edge of the first side wall 142, and a planar fourth 148side wall may extend perpendicularly between the first side wall 142 andthe second side wall 144 along a second lateral edge of the first sidewall 142. A planar end wall 149 may perpendicularly intersect the firstside wall 142, the second side wall 144, the third side wall 146, andthe fourth side wall 148, and the planar end wall 149 may comprise thetop portion 64 of the proximity switch 60. An open end 150 may provideaccess to an interior volume 152 of the housing 140. A pair of mountingflanges 154 a, 154 b may be secured to, or formed integrally with, thehousing 140 adjacent to the open end 150, and the mounting flanges 154a, 154 b may each have an aperture 155 that is adapted to receive a boltthat secures the housing 140 of the proximity switch 60 to a suitableportion of the bottom enclosure 28. The housing 140 may be made from acopper material and the pair of mounting flanges 154 a, 154 b may bemade from a brass material, and each of the pair of mounting flanges 154a, 154 b may be soldered or otherwise secured to the third side wall 146and the fourth side wall 148, respectively. If the pair of mountingflanges 154 a, 154 b is integrally formed with the housing 140, asillustrated in FIG. 14, then a first mounting flange 154 a may beintegrally formed with the third side wall 146 and a second mountingflange 154 b may be integrally formed with the fourth side wall 148. Thebody 140 having integrally formed mounting flanges 154 a, 154 b may bemade from a single piece of material (such as stainless steel) that isstamped and bent in one or more secondary operations. Because only asingle piece of material is used, and because no secondary bondingoperations (such as soldering) are required to secure the mountingflanges 154 a, 154 b to the body 140, a housing 140 formed from a singlepiece of material reduces both material costs and manufacturing costs.In addition, such integrally formed mounting flanges 154 a, 154 b do notseparate from the body 140 during seismic testing or other seismicevents, thereby maintaining the proximity switch 60 in it properposition.

Referring to FIGS. 8 and 9, the proximity switch 60 may include a switchassembly 156 that is disposed within the interior volume 152 of thehousing 140. The switch assembly may include a base 158, and the basemay include a fulcrum 160 formed on a first portion of the base. A lever162 may be pivotably coupled to the fulcrum 160 by a hinge pin 164. Adriver magnet 166 may be disposed within a cavity 168 formed in the base156, and the driver magnet 166 may have a substantially rectangularcross-sectional shape. The driver magnet 166 may have a height, width,and depth that closely correspond to the height, width, and depth of thecavity 168 such that the elongated driver magnet 166 can be receivedinto the cavity 168 such that a longitudinal axis of the driver magnet166 is parallel to a longitudinal axis of the base 156. A lip 170 mayextend along a pair of oppositely disposed lateral edges to maintain thedriver magnet 166 in a desired position within the cavity 168. Soconfigured, the longitudinal axis of the driver magnet may be parallelto a longitudinal axis of the lever 162 when the lever is balanced aboutthe hinge pin 164. The driver magnet 166 may be made from any suitablemagnetic material or combination of materials. For example, the drivermagnet 166 may be a samarium cobalt magnet.

The switch assembly 156 may also include an end cap 180 having aplurality of pins 182 that outwardly extend through the end cap 180.Each of the pins 182 may be electrically connected to contacts in theswitch assembly 156 in a manner which will be described in more detailbelow. The end cap 180 may be secured to an end portion of the base 156such that when the switch assembly 156 is disposed within the housing140, each of the plurality of pins 182 is substantially parallel to thelongitudinal axis of the housing 140 and a distal portion of each of theplurality of pins 182 projects out of the open end 150 of the housing140. The end cap 180 may also include a mounting shaft 184 that isrigidly coupled to the end cap 180 and that extends parallel to thelongitudinal axis of the housing.

As illustrated in FIG. 8, the proximity switch 60 may also include ashield 172 disposed within the interior volume 152 of the housing 140.The shield 172 may include a first wall 174 and a pair of parallellateral walls 176, 178 that each extend form opposing lateral edges ofthe first wall 174 such that the walls 174, 176, 178 defining a channelto receive and protect the switch assembly 156 within the interiorvolume 152 of the housing 140.

The switch assembly 156 of the proximity switch 60 may include drycontacts (i.e., contacts that are not initially connected to a voltagesource), such as form C dry contacts. For example, as illustrated inFIG. 11A, when the shaft 44 is in a first shaft position 61 in which thetarget magnet 58 is outside of a predetermined range (illustrated by thedashed area 196) of the top portion 64 of the proximity switch 60, thedriver magnet 166 may exert a magnetic force on the lever 162 (or anelement coupled to the lever 162) of suitable strength to maintain thelever 162 in a first position in which the lever 162 electricallycouples a “normally closed” contact N/C with a common contact C(schematically illustrated in FIG. 10A), with each of the normallyclosed contact N/C and the common contact C being electrically coupledto a corresponding pin 182 extending through the end cap 180. When thecommon contact C is electrically coupled to the normally closed contactN/C, the proximity switch 60 is in a first state 66.

The shaft 44 may be rotated from the first shaft position 61 to a secondshaft position 63, illustrated in FIG. 11B, in which the target magnet58 is within a predetermined range 196 of the top portion 64 of theproximity switch 60. In this second shaft position 63, the magneticforce between the lever 162 (or an element coupled to the lever) and thetarget magnet 58 becomes stronger than the magnetic force between thelever 162 (or an element coupled to the lever) and the driver magnet166. The stronger force between the target magnet 58 and the lever 162(or an element coupled to the lever) thereby causes the lever 162 topivot about the hinge pin 164 from the first position to a secondposition (shown schematically in FIG. 10B) in which the lever 162electrically couples a “normally open” contact N/O with the commoncontact C, with the normally open contact N/O being electrically coupledto a corresponding pin 182 extending through the end cap 180. With thelever 162 in this second position, the proximity switch 60 is in asecond state 70. The proximity switch 60 may be maintained in the secondstate 70 as long as the target magnet 58 is within a predetermined rangeof the top portion 64. However, when the target magnet 58 moves outsideof the predetermined range, the proximity switch 60 changes bias fromthe second state 70 to the first state 66.

As described above, the proximity switch 60 changes bias from a firststate 66 to a second state 70 when the target magnet 58 is within apredetermined range 196 of the top portion 64 of the proximity switch60. The predetermined range 196 may be defined by the size of themagnetic field generated by the driver magnet 166, the target magnet 58may be within the predetermined range 196 when any portion of themagnetic field generated by the target magnet 58 intersects any portionof the magnetic field generated by the driver magnet 166. Similarly, thetarget magnet 58 may be outside the predetermined range 196 when noportion of the magnetic field generated by the target magnet 58intersects a portion of the magnetic field generated by the drivermagnet 166. One having ordinary skill in the art would recognize thatthe predetermined range 196 can have a variety of sizes and shapes, andseveral factors may contribute to the size and shape of thepredetermined range 196, such as the relative size, thickness, and/orstrength of the driver magnet 166 and the target magnet 58, as well asthe vertical distance separating the driver magnet 166 and the targetmagnet 58, for example. By changing one of more of these variables, thesize of the predetermined range 196 may be adjusted to a desired size.For example, the target magnet may 58 may be within the predeterminedrange 196 when any portion of the target magnet 58 intersects anyportion of the top portion 64 of the proximity switch 60 when viewedalong the longitudinal axis of the shaft 44 from a point above thetarget support 52. One having ordinary skill in the art would alsorecognize that instead of the single pole, double throw configurationdescribed above, other configurations are also possible, such as, forexample, a double pole, double throw configuration.

As briefly explained above, both the driver magnet 166 and the targetmagnet 58 may be samarium cobalt magnets. Samarium cobalt magnets offera relatively large strength to area ratio compared to conventionalmagnets. Such a high strength to area ratio helps achieve increasedcontact pressure and a more positive snap action when the proximityswitch changes bias as described above.

The proximity switch 60 may be coupled to the bottom enclosure 28 in anysuitable manner. For example, as illustrated in FIG. 3, a planar supportplate 186 may be disposed on the base wall 30 of the bottom enclosure28, and the support plate 186 may be coupled to the base wall 30 by anymeans known in the art, such as by the use of adhesives or mechanicalcouplings. The support plate 186 may have pre-formed apertures 188 thatare adapted to receive the mounting shaft 184 and the bolts that extendthrough the apertures of the mounting flanges 154 a, 154 b to secure thehousing 140 of the proximity switch 60 to the support plate 186. Theapertures 188 may be disposed at any desirable locations in the supportplate 186, such as, for example, locations that allow the target magnet58 to be disposed adjacent to the top portion 64 of the proximity switch60.

As previously explained, the enclosed proximity switch assembly 10 mayinclude more than one proximity switch 60. For example, as illustratedin FIG. 3, a second proximity switch 60′ may also be mounted to thesupport plate 186, and the second proximity switch 60′ may be identicalto the first proximity switch 60 described above. The second proximityswitch 60′ may be disposed at any desired location on the support plate186 (or any other portion) of the bottom enclosure 28. For example, thefirst proximity switch 60 may be disposed such that the longitudinalaxes of the housing 140 is parallel to the longitudinal axis of theshaft 44, and the longitudinal axis of the housing 140 is offset fromthe longitudinal axis of the shaft 44 by a first distance. The secondproximity switch 60′ may be disposed such that the longitudinal axes ofthe housing 140′ is parallel to the longitudinal axis of the shaft 44,and the longitudinal axis of the housing 140 is offset from thelongitudinal axis of the shaft 44 by a distance that is substantiallyequal to the first distance. The first proximity switch 60 and thesecond proximity switch 60′ may be symmetrically disposed about theshaft 44 such that a horizontal reference line may pass through thelongitudinal axes of the shaft 44, the first proximity switch 60, andthe second proximity switch 60′. Said another way, when viewed along thelongitudinal axis of the shaft 44, the angle between a first horizontalline segment extending from the longitudinal axis of the shaft 44 to thelongitudinal axis of the first proximity switch 60 and a secondhorizontal line segment extending from the longitudinal axis of theshaft 44 to the longitudinal axis of the second proximity switch 60′ isapproximately 180°.

If three proximity switches are used, the three proximity switches mayalso be symmetrically disposed about the shaft 44. For example, theangle between a first horizontal line segment extending from thelongitudinal axis of the shaft 44 to the longitudinal axis of the firstproximity switch 60 and a second horizontal line segment extending fromthe longitudinal axis of the shaft 44 to the longitudinal axis of thesecond proximity switch 60′ is approximately 120°. In addition, theangle between the second horizontal line segment extending from thelongitudinal axis of the shaft 44 to the longitudinal axis of the secondproximity switch 60′ and a third horizontal line segment extending fromthe longitudinal axis of the shaft 44 to the longitudinal axis of thethird proximity switch 60″ is approximately 120°.

As illustrated in FIG. 7A, the enclosed proximity switch assembly 10 mayinclude one or more terminal strips 190. The one or more terminal strips190 may be coupled to the support plate 186 at any suitable locationsuch that the one or more terminal strips 190 does not interfere withthe rotation of the target support 52 about the shaft 44. The one ormore terminal strips 190 may be directly coupled to the support plate186 or may be coupled to a coupling element that is secured to thesupport plate 186 or any portion of the bottom enclosure 28, such as anupright bracket 191. The terminal strip 190 may have a ceramic insulatorbase using tubular shaped standoffs that mounting fasteners may passthrough. This arrangement provides an air gap between a mounting surfaceand the terminal strip 190, thereby reducing heat transfer between theterminal strip 190 and the mounting surface.

Each terminal strip 190 may be adapted to each receive one or more wires(not shown) that are electrically coupled to any of the plurality ofpins 182 of the proximity switch 60. The terminal strips 190 may also beadapted to receive one or more wires that may extend through the sideaperture 128 of the bottom enclosure 28, and these wires that extendthrough the side aperture 128 may be adapted to be connected to one ormore external devices, such as a controller or a diagnostic device. Theterminal strip 190 operates to electrically couple one of the wirescoupled to a pin 182 of the proximity switch 60 to a wire that extendsthrough the side aperture 128 in a manner known in the art. Instead of,or in addition to, the arrangement described above, any arrangement orcombinations or wires may be interconnected through the terminal strip190. For example a wire providing power may be interconnected to a wirethat is electrically coupled to a pin 182 of the proximity switch 60.Any suitable terminal strip 190 may be included in the enclosedproximity switch assembly 10. For example, the terminal strip 190 may beradiation tolerant, high temperature terminal strip. Such a terminalstrip 190 may be made from Ryton or a similar material. The terminalstrip 190 may also include metallic internal components to resistcorrosion. A transmission device (not shown) may be coupled to the oneor more terminal strips 190, and such a transmission device maycommunicate wirelessly one or more external devices, such as acontroller, to indicate the state of the one or more proximity switches60 to determine the position of the valve element of the control valve.

In operation, the enclosed proximity switch assembly 10 may be coupledto a valve element (not shown), such as the rotating stem of a controlvalve used for a nuclear application. The enclosed proximity switchassembly 10 may be coupled to the valve element by any means known inthe art, such as by a collar or other type of adapter. In addition, thebottom enclosure 28 may be coupled to a portion of the valve by, forexample, bolts that extend into apertures 194 disposed on a bottomsurface of the bottom enclosure 28. The enclosed proximity switchassembly 10 may be calibrated such that when the valve is in a firstposition, the shaft 44 is in the first shaft position 61 in which thetarget magnet 58 is outside of a predetermined range of the top portion64 of the proximity switch 60 such that the proximity switch 60 is inthe first state 66. However, when the valve is in a second position, theshaft 44 is rotated into a second shaft position 63 in which the targetmagnet 58 is within a predetermined range of the top portion 64 of theproximity switch 60 such that the proximity switch 60 moves to a secondstate 70. As explained previously, the proximity switch 60 is maintainedin the second state 70 as long as the target magnet 58 is within thepredetermined range of the top portion 64. When the target magnet 58 ismoved outside of the predetermined range, the proximity switch 60changes bias from the second state 70 to the first state 66. One havingordinary skill in the art would recognize that the shaft 44 could bemaintained in the second shaft position 63 in which the target magnet 58is within a predetermined range of the top portion 64 of the proximityswitch 60 such that the proximity switch 60 is in a second state 70, andthe shaft 44 could be rotated into the first shaft position 61, therebycausing the proximity switch to move to the first state 66, when thecontrol element coupled to the shaft 44 is rotated or otherwisedisplaced. In this configuration, one having ordinary skill in the artwould recognize that the normally open contact and normally closedcontact illustrated in FIGS. 10A and 10B would switch roles.

If additional proximity switches 60 are used, the target magnet 58 (oran additional target magnet coupled to the target support 52) may changethe bias of the additional proximity switch 60 from the first state 66to the second state 70 (and vice versa) as explained above. A controller(or other device) that is connected to the wires that are connected tothe terminal strips 190 may indicate the state of the one or moreproximity switches 60 to determine the position of the valve element ofthe control valve.

Additional features may be incorporated into the enclosed proximityswitch assembly 10, such as a magnetic interlock indicator (not shown)disposed on the outside of the top enclosure 12 or bottom enclosure 28.The magnetic interlock indicator may indicate whether the proximityswitch 60 is in the first state 66 or the second state 70. The magneticinterlock indicator may have a machined post design using a knob in thetop enclosure 12 or the magnetic interlock indicator may include africtionless magnetic float driven by the magnetic pull of the targetmagnet. The enclosed proximity switch assembly 10 may also include anattached solenoid valve.

The embodiments of the enclosed proximity switch assembly 10 describedabove provide a contained environment for use in hazardous environments,such as nuclear applications. More specifically, the enclosed proximityswitch assembly 10 is intended to withstand temperatures and pressuresthat occur during a containment accident or a LOCA (loss of coolantaccident) at a nuclear facility, and the enclosed proximity switchassembly 10 may be an explosion-proof enclosure. This level ofprotection is due in part to the elimination of potential leakpathsthrough the top enclosure 12 due to a shaft aperture (or other point ofingress) because the interior bore portion 24 of the shaft protrusion 20is an enclosed volume that is not in fluid communication with theexterior of the top enclosure 12. Other leakpaths are prevented byseals, such as seals 116, 132, which may be fabricated from a radiationtolerant, high temperature silicone material. The wires that extend fromthe terminal strips 190 (or directly from the one or more proximityswitches 60) through the side aperture 128 of the bottom enclosure 28may be protected by a radiation resistant conduit (not shown) that maybe sealingly coupled to the side aperture to further prevent potentialleakpaths.

The enclosed proximity switch assembly 10 described above also providesa modular design that allows the number of and layout of proximityswitches 60, as well as other components, to be changed for a desiredapplication, thereby reducing the cost associated with replacing anentire assembly when a configuration is to be modified. In addition, onehaving ordinary skill in the art would recognize that a nuclear junctionbox is not necessary with the enclosed proximity switch assembly 10, andthe enclosed proximity switch assembly 10 requires less piping thanconventional switch enclosures, which both further reduce costs andrequire less labor to install.

While various embodiments have been described above, this disclosure isnot intended to be limited thereto. Variations can be made to thedisclosed embodiments that are still within the scope of the appendedclaims.

What is claimed is:
 1. A target support for supporting a target magnetwithin an enclosed proximity switch assembly, the target supportcomprising: a hub having a body portion that extends along alongitudinal axis, the body portion including an outer surface and ashaft aperture that extends along the longitudinal axis, the shaftaperture adapted to receive a portion of a shaft that extends along thelongitudinal axis, wherein the body portion further includes one or morethreaded body apertures that extend from the outer surface to the shaftaperture; a magnet support non-rotatably secured to the hub, the magnetsupport having a base portion that extends in a direction normal to thelongitudinal axis, the base portion including a planar top surface, themagnet support further including a side wall that upwardly extends fromthe top surface of the base portion, the side wall being partiallydefined by an inner surface; one or more target magnets disposed on thetop surface of the base portion of the magnet support between a portionof the hub and the inner surface of the side wall of the magnet support;a clamp plate having a planar bottom surface and a shaft apertureadapted to receive a portion of the shaft, the clamp plate being securedto the hub such that the bottom surface of the clamp plate isimmediately adjacent to or in contact with a top surface of the hub andsuch that the bottom surface of the clamp plate is also immediatelyadjacent to or in contact with a top surface of the one or more targetmagnets; a set screw adapted to threadably engage one of the one or morebody apertures such that a distal end of the set screw contacts an outersurface of the shaft to non-rotatably secure the target support to theshaft, wherein a minimum torque of 150 inch-ounces is applied to the setscrew, and a high-temperature potting applied to one of a portion of theset screw or a portion of the one of the one or more body apertures tosecure the set screw within the one of the one or more body apertures.2. The target support of claim 1, wherein the hub and the magnet supportare integrally formed as a single, unitary part.
 3. The target supportof claim 1, wherein the body portion of the hub is received into acentral aperture formed in the base portion of the magnet support. 4.The target support of claim 1, wherein the one or more body aperturesmay extend normal to the longitudinal axis.
 5. The target support ofclaim 4, wherein the hub includes a first body aperture, a second bodyaperture, a third body aperture, and a fourth body aperture that eachextends normal to the longitudinal axis.
 6. The target support of claim5, wherein the first and second body apertures are longitudinallyaligned and offset by a longitudinal distance.
 7. The target support ofclaim 6, wherein the third body aperture is radially aligned with thefirst body aperture and the fourth body aperture is radially alignedwith the second body aperture.
 8. The target support of claim 1, whereinthe high-temperature potting is an epoxy.